St Columba's By The Castle Episcopal Church, 14 Johnston Terrace, Edinburgh

St Columba's by the Castle Episcopal Church, located at 14 Johnston Terrace in Edinburgh, was built between 1846 and 1847 by John Henderson. It is an Early English Gothic church with a simple, six-bay aisless plan and a pitched roof. The building presents a single storey to Johnston Terrace and three storeys to the rear, and features a sham square tower to the west with a crenellated parapet. The exterior is constructed of lightly stugged, coursed sandstone, with squared and snecked stone to the rear. Bays are flanked by buttresses.

The north (Johnston Terrace) elevation has a slightly recessed bay on the outer right, which contains a timber panelled door with decorative cast-iron hinges and a fanlight, set within a shafted and hoodmoulded cusped surround with carved label stops. Above this are two quatrefoil-headed, two-light windows set within the crenellated towerhead. Four stepped, three-light lancets define the nave. A lower, slightly recessed bay on the outer left has a small, engaged octagonal turret in the re-entrant angle, and a quatrefoil-headed, two-light window with a hoodmould and carved label stops to the chancel. An angle buttress is situated on the outer left. A bracketed eaves course and parapet complete the elevation.

The east (Victoria Terrace) elevation is stepped to match the angle of the slope, with a blocked pointed-arched window to the chancel.

The south (rear) elevation features a later projecting timber porch to the ground at the outer left, with paired lancets above allowing light to the stairwell. The four centre bays are flanked by buttresses, with stepped, three-light lancets providing light to a hall on the ground floor and single lancets to the church above. A projecting bay extends to the outer right, featuring another projecting timber porch to the ground and small paired lancets above the stairwell.

The interior showcases a collar-braced timber roof. The pointed-arched chancel contains a mural which conceals a blocked window, alongside a carved stone altar, timber panelling, and sedilia. The pulpit is corbelled out to the northeast and accessed via a timber boarded door with wrought-iron hinges in a shoulder-arched surround. A cusped aumbry is located in the north wall, containing a bronze door dating to approximately 1914. A richly carved stone font is also present. A triple-arched gallery is now blocked. A hall on the lower level has a lowered ceiling, a timber floor, and cast-iron columns.

Exterior features include an ashlar-coped retaining wall and a flagged terraced garden to the south. The church contains plate tracery, small pane leaded glass, and stained glass, while the lower floors have plain glazing. The roof is covered with greenish-grey slates, and incorporates cross-finialled stone skews. Decorative cast-iron down pipes with hoppers are also present.